This proposal builds upon a five year research project, SEARCHfor Diabetes in Youth, its standardized data collection effort, experienced investigator team, established case ascertainment infrastructure, and ethnically diverse population base. This is a common, integrated application from the six SEARCHclinical sites, which proposes to continue and expand the work performed by SEARCH in order to address the following specific research aims: AIM 1: Prospectively ascertain newly diagnosed (2006-2009) incident cases age less than 20 years in order to estimate temporal trends in incidence of DM in youth; AIM 2: Conduct longitudinal follow-up of incident cases already recruited to SEARCH in 2002-2005 in order to document the evolution of newly diagnosed DMaccording to clinical and biochemical factors; AIM 3: Complete analyses initiated in the first five years of SEARCH and expand the scope of quality of care assessment to encompass more broadly defined concepts and measures of quality; AIM 4: Develop and validate simple and low-cost case definitions and classifications of DMtypes in youth that can be used for public health surveillance. The novelty of this proposal includes its comprehensive nature that brings together major and timely facets of childhood DM research: an epidemiologic study, unique in the United States, of temporal trends in the incidence of DM in youth; a pathophysiologic component addressing the natural history of DM in youth; a study of processes of care and quality of life; and a public health perspective on case classification of DM in youth. This research is critically important to public health as it will provide information about whether and how much DM is increasing among youth of different racial/ ethnic groups in the United States, about how DM impacts on the physical health, including complications, as well as valuable data regarding the quality of care and the quality of life of these youth. The population under surveillance at the Colorado SEARCHsite consists of all youth age < 20 years a) residing in the state of Colorado (63 counties) in 2006-2009, and b)members of three American Indian populations in Arizona and New Mexico, who participated in SEARCH1.These include: the Navajo Nation, the White Mountain Apache Reservation and the Gila River Pima Reservation. The estimated total population under surveillance at the Colorado SEARCHsite is -1.4million youth age < 20 years, which makes our center the largest current SEARCHsite.